Little is known of Ebbesen's background. He seems to have belonged to the Jutlandish gentry. Like many other of his class, he probably supported the Holstein occupiers during the years of chaos, but later turned against them and when Count Gerhard campaigned in Jutland in 1340, Ebbesen supported the Jutlandish guerrillas. On 1 April, he and 47 of his warriors entered Randers and hid until nightfall. They got into the Count's headquarters and entered his bedroom. They cut off the count's head over the end of the bed. Not wishing the act to be secret, Ebbesen's men beat a drum and shouted that the Count had been executed. When the Holsteiners gave chase, Ebbesen and his men fled toward the bridge over the River Guden. Svend Trøst, one of Ebbesen's men had weakened the bridge, and as soon as Ebbesen and his followers had crossed, they pulled the bridge down and made their escape, losing just a single man.
During the following rebellion, Niels Ebbesen played a main role in the resistance but he was killed the same year during a fight against the Germans. 2000 Danes laid siege to Skanderborg Castle in April 1340. A relief force of 600 German knights and a simultaneous attack from the castle drove the Danes back into their wagon fortress on Nun Hill. The ring of wagons was breached, and Ebbesen and his men were surrounded and butchered by the Germans.
A ballad dealing with the killing of Count Gerhard by Ebbesen is translated into English in Alexander Gray's Historical Ballads of Denmark (Edinburgh University Press, 1958).
Traditionally, Niels Ebbesen has been regarded one of the great heroes of medieval Danish history; the "tyrant slayer" whose action marked the beginning of the liberation of Denmark. Yet others disapproved of his act, regarding it as simply murder. Whether his motives were purely national or partly private is impossible to know. This has not prevented both romantic Danish poetry and modern ballads from praising him as a freedom fighter.
In 1942, during the German occupation of Denmark in the Second World War, a play about Ebbesen's rebellion was penned by the dramatist Kaj Munk. The Nazi occupiers banned the play and murdered its playwright.
- Huitfeldt, Arild. Danmarks Riges Krønike
- Dansk Biografisk Leksikon, vol. 4, Copenh. 1980.
- Politikens Danmarkshistorie, vol. 4 by Erik Kjersgaard, Copenh. 1962.
- Jyske Krønike, transl. by Rikke Agnete Olsen. Aarhus, 1995.